1. Field of the Invention
This invention concerns fluid pressure connections and more particularly arrangements for connecting together modular or stackable manifold units having mating planar surfaces in which are formed fluid pressure parts which must be sealed by the mating engagement.
2. Description of the Prior Art
In providing hydraulic equipment of a complicated nature such as are utilized in machine tool and transfer line applications, it is desirable to have the capability for making modifications to existing designs or machines to provide additional hydraulic cylinders, way units, etc. at a given point. In recent years the great advantages accruing from an ability to add such hydraulic equipment to existing machines or designs by the use of modular or stackable manifold units have become recognized. In these arrangements, the hydraulic supply lines from the hydraulic pressure source is connected via manifold units, which receive the pressure return and supply lines from the hydraulic pressure source and via internal passages provides appropriate ports for connections to the associated control valves and ports for connection to the hydraulic device. These manifolds are adapted to be "stacked" by virtue of a capability for securing together mating faces of one or more of such manifold units. By having openings on the mating face aligned with the pressure return and supply lines, and by merely adding a manifold unit, all of the connections necessary to add one or more of such hydraulic devices and valving can be carried out by simply fastening an additional manifold unit to the existing manifold unit and installing the valve and actuator device by connections to the manifold unit. Since most of the fluid pressure connections are via internal passages in the manifold block, installation is greatly simplified, and the number of hydraulic connection seals, lines, etc., is considerably reduced. The incidence of leakage thus would also be considerably reduced, in turn improving the reliability of the equipment and reducing down time as well as maintenance cost.
However, a convenient and effective means for securing together the mating faces of adjacent manifold blocks has not heretofore been provided. Current approaches include the use of long tie rod bolts passing through openings extending through all of the stacked manifold block members, which would then be drawn together by tightening cooperating threaded nuts, engaging each of the long bolt members. This approach necessitates the use of tie rod members of different lengths, since the connection would require replacement of existing tie rods as additional manifold blocks are added to the assembly.
Furthermore, the bolt members are stressed in tension and in hydraulic units considerable pressure may be exerted tending to stretch the bolt members, and reducing the reliability of the sealing between blocks produced by the tie rod especially in applications in which the tie rods are quite long in order to accomodate the length of the stack manifold blocks.
Other approaches involve the use of flanges machined or otherwise formed into the sides of the manifold blocks adjacent the mating surfaces, with relatively short bolts passing through aligned openings of the bolts in the abutting flanges. This approach, likewise, involves stressing in tension and bending of the flanges, and since the manifold assemblies are typically fabricated from aluminum, the stiffness of the flanges may not be adaquate to ensure reliable sealing. Also, the accessibility of such bolts for assembly is not optimal since they extend adjacent side surfaces of the manifold block. Furthermore, the flanges may add significantly to the fabrication expenses involved, since extensive milling operations are usually required to form the flanges integral with the manifold blocks.
Other arrangements have included dove-tailing surfaces formed on the manifold blocks but this approach does not provide an adequate force tending to draw together the mating faces to produce a good seal and are accordingly not appropriate for hydraulic applications involving substantial pressures which must be completely sealed.
Similarly, arrangements have been provided in which spring clips are adapted to draw together the mating surfaces, but these forces are, likewise inadequate for proper sealing for all but a few of the applications for such equipment.
It is therefore an object of the present invention to provide a connection arrangement to secure together mating faces of such manifold blocks, which provides adequate sealing pressure between the mating faces, capable of resisting relatively great separation pressures.
It is a further object of the present invention to provide such a connection means which does not involve the use of connector elements unique to the sizing of the manifold units or the number of units interconnected together.
It is yet another object of the present invention to provide such a connection arrangement which does not involve extensive machining or complex structural features on the manifold bodies.
Finally, it is an object of the present invention to provide such a connection arrangement which is relatively convenient to install such, as to be easily and simply assembled by the machine builder.